/**
 * 录音类（针对content-type为application/octem-stream 的使用）
 * @param {*} stream 
 * @param {*} config 
 */
const HZRecorder = function (stream, config) {
  config = config || {};
  config.sampleBits = config.sampleBits || 8;      //采样数位 8, 16  
  config.sampleRate = config.sampleRate || (44100 / 6);   //采样率(1/6 44100)  


  //创建一个音频环境对象  
  audioContext = window.AudioContext || window.webkitAudioContext;
  var context = new audioContext();

  //将声音输入这个对像  
  var audioInput = context.createMediaStreamSource(stream);

  //设置音量节点  
  var volume = context.createGain();
  audioInput.connect(volume);

  //创建缓存，用来缓存声音  
  var bufferSize = 4096;

  // 创建声音的缓存节点，createScriptProcessor方法的  
  // 第二个和第三个参数指的是输入和输出都是双声道。  
  var recorder = context.createScriptProcessor(bufferSize, 2, 2);

  var audioData = {
    size: 0          //录音文件长度  
    , buffer: []     //录音缓存  
    , inputSampleRate: context.sampleRate    //输入采样率  
    , inputSampleBits: 16       //输入采样数位 8, 16  
    , outputSampleRate: config.sampleRate    //输出采样率  
    , oututSampleBits: config.sampleBits       //输出采样数位 8, 16  
    , input: function (data) {
      this.buffer.push(new Float32Array(data));
      this.size += data.length;
    }
    , compress: function () { //合并压缩  
      //合并  
      var data = new Float32Array(this.size);
      var offset = 0;
      for (var i = 0; i < this.buffer.length; i++) {
        data.set(this.buffer[i], offset);
        offset += this.buffer[i].length;
      }
      //压缩  
      var compression = parseInt(this.inputSampleRate / this.outputSampleRate);
      var length = data.length / compression;
      var result = new Float32Array(length);
      var index = 0, j = 0;
      while (index < length) {
        result[index] = data[j];
        j += compression;
        index++;
      }
      return result;
    }
    , encodeWAV: function () {
      var sampleRate = Math.min(this.inputSampleRate, this.outputSampleRate);
      var sampleBits = Math.min(this.inputSampleBits, this.oututSampleBits);
      var bytes = this.compress();
      var dataLength = bytes.length * (sampleBits / 8);
      var buffer = new ArrayBuffer(44 + dataLength);
      var data = new DataView(buffer);

      var channelCount = 1;//单声道  
      var offset = 0;

      var writeString = function (str) {
        for (var i = 0; i < str.length; i++) {
          data.setUint8(offset + i, str.charCodeAt(i));
        }
      };

      // 资源交换文件标识符   
      writeString('RIFF'); offset += 4;
      // 下个地址开始到文件尾总字节数,即文件大小-8   
      data.setUint32(offset, 36 + dataLength, true); offset += 4;
      // WAV文件标志  
      writeString('WAVE'); offset += 4;
      // 波形格式标志   
      writeString('fmt '); offset += 4;
      // 过滤字节,一般为 0x10 = 16   
      data.setUint32(offset, 16, true); offset += 4;
      // 格式类别 (PCM形式采样数据)   
      data.setUint16(offset, 1, true); offset += 2;
      // 通道数   
      data.setUint16(offset, channelCount, true); offset += 2;
      // 采样率,每秒样本数,表示每个通道的播放速度   
      data.setUint32(offset, sampleRate, true); offset += 4;
      // 波形数据传输率 (每秒平均字节数) 单声道×每秒数据位数×每样本数据位/8   
      data.setUint32(offset, channelCount * sampleRate * (sampleBits / 8), true); offset += 4;
      // 快数据调整数 采样一次占用字节数 单声道×每样本的数据位数/8   
      data.setUint16(offset, channelCount * (sampleBits / 8), true); offset += 2;
      // 每样本数据位数   
      data.setUint16(offset, sampleBits, true); offset += 2;
      // 数据标识符   
      writeString('data'); offset += 4;
      // 采样数据总数,即数据总大小-44   
      data.setUint32(offset, dataLength, true); offset += 4;
      // 写入采样数据   
      if (sampleBits === 8) {
        for (var i = 0; i < bytes.length; i++, offset++) {
          var s = Math.max(-1, Math.min(1, bytes[i]));
          var val = s < 0 ? s * 0x8000 : s * 0x7FFF;
          val = parseInt(255 / (65535 / (val + 32768)));
          data.setInt8(offset, val, true);
        }
      } else {
        for (var i = 0; i < bytes.length; i++, offset += 2) {
          var s = Math.max(-1, Math.min(1, bytes[i]));
          data.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
        }
      }

      return new Blob([data], { type: 'audio/wav' });
    }
  };
  //开始录音  
  this.start = function () {
    audioInput.connect(recorder);
    recorder.connect(context.destination);
  };

  //停止  
  this.stop = function () {
    recorder.disconnect();
  };

  // 结束
  this.end = function () {
    context.close();
  };

  // 继续
  this.again = function () {
    recorder.connect(context.destination);
  };

  //获取音频文件  
  this.getBlob = function () {
    this.stop();
    return audioData.encodeWAV();
  };

  //回放  
  this.play = function (audio) {
    audio.src = window.URL.createObjectURL(this.getBlob());
  };

  //上传  
  this.upload = function (url, succ, fail) {
    const xhr = new XMLHttpRequest();
    xhr.overrideMimeType("application/octet-stream")
    // xhr.upload.addEventListener('progress', function (e) {
    // }, false);
    xhr.addEventListener('load', function (e) {
      succ(xhr.response)
    }, false);
    xhr.addEventListener('error', function (e) {
      fail(xhr.response);
    }, false);
    xhr.addEventListener('abort', function (e) {
      fail(xhr.response);
    }, false);
    xhr.open('POST', url);
    if(xhr.sendAsBinary){
      xhr.sendAsBinary(this.getBlob());
    }else{
      xhr.send(this.getBlob());
    }
  };

  //音频采集  
  recorder.onaudioprocess = function (e) {
    audioData.input(e.inputBuffer.getChannelData(0));
  };
}

/**
 * 多浏览器兼容
 * @param {*} videoConfig 参数配置
 * @param {*} succ 成功回调
 * @param {*} fail 失败回调
 * @returns promise
 */
HZRecorder.compatibleMedia = async function(videoConfig) {
	let streamPromise // 视频promise
	if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia){
		// 最新标准API
		streamPromise = await navigator.mediaDevices.getUserMedia(videoConfig)
	} else if (navigator.webkitGetUserMedia){
		// webkit内核浏览器
		streamPromise = await navigator.webkitGetUserMedia(videoConfig)
	} else if (navigator.mozGetUserMedia){
		// Firefox浏览器
		streamPromise = await navagator.mozGetUserMedia(videoConfig)
	} else if (navigator.getUserMedia){
		// 旧版API
		streamPromise = await navigator.getUserMedia(videoConfig)
	}
	return streamPromise
}
/**
 * 是否支持录音
 * @returns 支持直接返回录音类实例 : 返回false
 */
HZRecorder.ready = async function() {
	let instance // 录音类实例（ready ok） | false （ready no）
	await HZRecorder.compatibleMedia({ audio: true }).then(stream => {
		instance = new HZRecorder(stream);
	}).catch(() => {
		instance = false
	})
	return instance
}